Even if red meat could be deemed healthy, humans don't require anything nutritionally from it, and it's made of sentient beings that don't want to be killed.
Also, it isn't sustainable for all humans to eat red meat - we could end world hunger IMMEDIATELY if those of us eating red meat would switch to plant sources of nutrients.
Human meat is just as healthy for us as the flesh of cows, pigs, dogs, whales, cats, goats, and other sources of red meat. Most of us know it's wrong to enslave, breed, and kill other humans, but for some reason many of us still do it to cows, pigs, dogs, whales, cats, goats, and several other intelligent mammals.
When we know these facts, it takes a great amount of cognitive dissonance to continue stuffing our faces with dead factory-farmed innocent individuals, no matter how often we tell ourselves "it's healthy".